The real Eleodes suturalis…
September 16, 2010 2 Comments
I recently posted a photograph of a clown beetle (Eleodes hispilabris) (family Tenebrionidae) that I found last July in the Glass Mountains of northwestern Oklahoma. I had encountered that individual while stumbling through the mixed-grass prairie in the middle of the night in search of the Great Plains giant tiger beetle (Amblycheila cylindriformis). Although I eventually found the latter species, it took a few hours, during which time I was forced to examine numerous individuals of another clown beetle, Eleodes suturalis – perhaps the most conspicuously common clown beetle in the Great Plains. I didn’t bother to take photographs of them, focused as I was on my tiger beetle search and owing to the fact that this was not the first time I’d encountered that species in abundance (the first time being many, many years ago as they crossed the highway en masse just a few miles north of the Glass Mountains in Barber Co. Kansas). In fact, I was becoming rather annoyed with them due to their great similarity in size and coloration to the object of my desire¹, and only when I found the previously photographed individual doing the defensive “head stand” so characteristic of the group did I relent and break out the camera for a series of shots (not easy in the dark of night).
¹ Wrigley (2008) even suggested a mimetic association for Amblycheila cylindriformis and Eleodes suturalis due to their similarity in size, shape and coloration (black with a reddish-brown sutural stripe).
Of course, that individual turned out not to be E. suturalis, but the closely related species E. hispilabris, a fact that I did not realize until several days later as I was examining the photographs more closely. Fortunately, I happened to bring home with me a live individual of what truly represents E. suturalis, which I show in these photographs. I’m not sure exactly why I brought a live one home with me – I’ve done more and more of this in recent years, mostly just to observe them and see what they do.² I think in this case, I was intrigued by the possible mimetic association between this species and A. cylindriformis and wanted an individual for comparison with the several live A. cylindriformis individuals that I also brought back with me.
² The singular focus on collecting “specimens” that I had during my younger years seems to be giving way to a desire to know more about species as living entities and not just their external morphology.
Unlike E. hispilabris (my identification of which I only consider tentative), there can be little doubt that the individual in these photographs represents E. suturalis. No other clown beetle in the Great Plains exhibits the sharply laterally carinate elytra and broadly explanate (spread outward flatly) pronotum (Bernett 2008). The reddish-brown sutural stripe of the distinctly flattened elytra is also commonly seen in this species, although occasional individuals of a few other clown beetle species exhibit the stripe as well (including E. hispilabris, which likely was the reason I assumed it represented E. suturalis). All of the characters mentioned above can be seen in the photographs shown here. However, I nevertheless find the photos rather unsatisfying. If you think you know why, feel free to comment, otherwise you can wait for the “better” photos…
Photo Details: Canon 50D w/ 100mm macro lens (ISO 100, 1/250 sec, f/18), Canon MT-24EX flash w/ Sto-Fen diffusers. Typical post-processing (levels, minor cropping, unsharp mask).
Bernett, A. 2008. The genus Eleodes Eschscholtz (Coleoptera: Tenebrionidae) of eastern Colorado. Journal of the Kansas Entomological Society 81(4):377–391.
Wrigley, R. A. 2008. Insect collecting in Mid-western USA, July 2007. The Entomological Society of Manitoba Newsletter 35(2):5–9.
Copyright © Ted C. MacRae 2010